A proposed regulation that would require nursing homes to hire independent pharmacists to oversee residents' medication plan regimens could have a huge impact on pharmacy services suppliers such as Omnicare and PharMerica.

According to the proposed rule, relationships between nursing homes and pharmacy suppliers could “conflict with the best interests of nursing home residents.” Therefore, the proposal to mandate independent pharmacists was made.

The regulation also has implications for Omnicare's hostile takeover bid for rival PharMerica, according to observers.

News of the Centers for Medicare & Medicaid Services proposed rule made shares of Omnicare and PharMerica, the top two nursing home pharmacy suppliers, drop sharply Tuesday. Omnicare shares fell 12% to $21.62, while PharMerica's fell 15% to $11.91, Bloomberg News reported.

Omnicare announced Wednesday that it is extending its offer to purchase all outstanding shares of PharMerica until Dec. 2. Its previous offer was to expire at midnight Tuesday (Oct. 4).

Drug substitutions saved the government $13 million last year, but more drug substitutions under Medicare Part B would have saved an additional $6 million, the Office of Inspector General for Health and Human Services concluded in a recent report to Congress.